The present invention relates to constant velocity joints and more particularly, concerns constant velocity joint of the counter track type.
Constant velocity fixed ball joints in the form of a counter track joint, having an outer joint part with outer tracks, an inner joint part with inner tracks, torque transmitting balls which are received in pairs of tracks consisting of outer tracks and inner tracks, and a ball cage with cage windows in which the balls are held in a common plane and are guided on to the angle-bisecting plane when the joint is articulated are such joints, wherein first outer tracks, together with first inner tracks, form first pairs of tracks whose control angles open in a first axial direction R1, and second outer tracks, together with second inner tracks, form second pairs of tracks whose control angles open in a second axial direction R2. The control angles are defined as angles between the tangents at the ball contact points in the tracks when the joint is in the aligned condition. The control angles are formed by an axial offset of the centers of curvature of the outer tracks and of the inner tracks in the respective component relative to a central joint plane defined by the centers of the balls when the joint is in the aligned condition.
With constant velocity fixed ball joints of this type, provision is generally made for the outer face of the cage and/or the inner face of the cage to be approximately spherical in shape for the purpose of being supported relative to the outer joint part and/or the inner joint part. When assembling such joints, use is made of the known over-articulating method when mounting the balls, i.e. first the outer joint part, the ball cage and the inner joint part are inserted into one another without the balls, whereupon excessively large articulation angles which cannot be achieved under operational conditions are set between the outer joint part and the inner joint part. The balls are then inserted into the cage windows from the outside in different articulation positions.
It would therefore be desirable to provide an improved joint of the foregoing type which permits a simplified method of manufacture and/or assembly.
A constant velocity fixed ball joint having improved assembly is provided. In the constant velocity fixed ball joint disclosed, the outer joint part forms a first stop-and-guiding face for a spherical outer face of the ball cage, and the first stop-and-guiding face is undercut-free if viewed in a first axial direction. A securing element at the outer joint part forms a second stop-and-guiding face for a spherical outer face of the ball cage or of the inner joint part. The inner face of the outer joint part is undercut-free if viewed in a second axial direction. The inner joint part can be introduced coaxially into the ball cage in the second axial direction. In particular, the inner face of the ball cage is also undercut-free if viewed in the second axial direction. The above-mentioned characteristics allow the joint to be assembled entirely axially, i.e. the outer joint part, the ball cage with the inserted balls and the inner joint part can be inserted into one another in coaxial positions. The outer joint part, the ball cage and the inner joint part are stacked one behind the other in a starting position. First the balls, with their centers, are passed through the aperture plane of the outer joint part and, only thereafter, by moving on the joint inner part, the balls enter the outer tracks in the outer joint part and the inner tracks in the inner joint part. After the ball cage has stopped against the stop-and-guiding face in the outer joint part, the joint is secured by a securing element attached to the outer joint part. To the extent that reference is made to the joint aperture of the outer joint part, in the assembly operation of a joint with a separately produced base or, in the case of disc joints, this can refer to the aperture pointing towards the joint base or attachment flange; and the securing element to be bolted on, can be the joint base itself or an annular or cover element inserted between the outer joint part and the joint base.
When applying the above-mentioned assembly method, it is possible, in one embodiment of the invention, for the inner joint part to be produced so as to be integral with a joint journal or with a shaft shank.
According to another embodiment, the ball cage, on its inside, forms a third stop-and-guiding face for a spherical outer face of the inner joint part. However, such a contact between the inner joint part and the ball cage is not absolutely essential. Axial fixing of the inner joint part relative to the ball cage can also be effected in both axial directions indirectly via ball tracks, balls and cage windows.
As already mentioned in connection with the possible assembly, the securing element can be an annular additional element attached to the joint aperture of the outer joint part or individual wedge elements attached to, or formed on to, the joint aperture of the outer joint part, with the second axial direction pointing from the joint aperture to the joint center. Alternatively, the securing element can be the joint base produced separately from the outer joint part or a ring- or cover-shaped additional element inserted between the outer joint part and the joint base, with the second axial direction pointing from the joint base to the joint center.
Special advantages of the inventive joint are provided in that, as a result of its undercut-free inner contour, the cage can be produced advantageously from a production-technical point of view, by non-cutting forming by a punch. Also, the guiding faces for the outer joint part for the ball cage are undercut-free, which, at least as far as the cage faces are concerned, makes it possible for these to be produced in a simplified way by forming same in a non-chip producing way. Simplifications are also achieved as regards the production of the outer joint part by producing an undercut-free inner face which can also be produced advantageously by a non-chip producing forming operation, using an undivided tool. If, in accordance with another embodiment, at least part of the pairs of tracks is undercut-free, it is advantageous to position the respective undercut-free tracks in the outer joint part in the same direction as the undercut-free stop-and-guiding face for the ball cage. As a result, a substantial part of the inner surface of the outer joint part can be formed by a one-piece inner punch.
Other advantages of the invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings.